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Label Generation Rules for Korean

Overview

This document specifies a set of Label Generation Rules (LGR) for the Korean language using a language-specific repertoire for the second level domain or domains identified above. The format of this file follows [RFC 7940]. This LGR is adapted from the “Reference LGR for the Second Level for the Korean Language” [Ref-LGR-ko-Kore], for details, see Change History below.

Standalone LGR: This LGR is designed to be used in a zone that does not cater to IDNs other than those valid under this LGR. Following existing practice, this LGR also supports ASCII letters and where applicable accounts for any interaction with the remainder of the repertoire.

Repertoire

For the Hangul syllables used to write the Korean language, all references converget on the set of 11,172 Hangul syllables contained in Unicode since version 2.0. These Hangul Syllables are sometimes called Johab, the name originating from the initial standard in which they were defined: KSC C 5601-1992 , and the encoding in which they were represented in that standard. One part of that standard also defines a subset (known as Wansung) which consists of 2,350 Hangul syllables. KSC C5601-1992 later became KS X 1001:2004.

The text in [700] recommends to only use the 2,350 Wansung code points, but given the large deployment of platforms supporting the full Johab repertoire, this recommendation is considered unnecessary in the context of this LGR.

At time of development there was no established practice for the use of Korean ideographs (Hanja) derived from Chinese ideographs (Hanzi) in IDNA labels. Hanja characters are rarely used in Korea (North or South). Therefore it does not seem necessary to add them in a Second Level LGR for Korean Language at this point.

For the second level, the repertoire has been augmented with the ASCII digits, U+0030 0 to U+0039 9; the ASCII lowercase letters, U+0061 a to U+007A z; and U+002D - HYPHEN-MINUS, for a total of 11,209 repertoire elements.

Unlike many other non-Latin Second Level Reference LGRs, the Korean language LGR includes the basic ASCII Latin set (a to z) because it is common practice in Korean text to mix Korean and ASCII. Therefore it does not create confusability or additional security risks in the context of a Second Level LGR for the Korean language. It is also supported by current IDNA practice, see [700], for example.

Variants

No variants are applicable when using the LGR in a standalone fashion.

Character Classes

This LGR does not define named character classes.

Rules

Common Rules

By default, the LGR includes the rules and actions to implement the following restrictions mandated by the IDNA protocol. They are marked with ⍟.

• Hyphen Restrictions — restrictions on the allowable placement of hyphens (no leading/ending hyphen and no hyphen in positions 3 and 4). These restrictions are described in Section 4.2.3.1 of RFC 5891 [150]. They are implemented here as context rule on U+002D (-) HYPHEN-MINUS.
• Leading Combining Marks — restrictions on the allowable placement of combining marks (no leading combining mark). This rule is described in Section 4.2.3.2 of RFC 5891 [150].

Actions

This LGR includes the default actions for LGRs as well as the action needed to invalidate labels with misplaced combining marks. They are marked with ⍟. For a description see [RFC 7940].

Methodology and Contributors

The LGR in this document has been adapted from the corresponding Reference LGR for the Second Level. The Second Level Reference LGR for the Korean Language was developed by Michel Suignard and Asmus Freytag, verified in expert reviews by Lu Qin and Wil Tan, and based on multiple open public consultations.

Changes from Version Dated 10 October 2016

Language tags have been updated.

Changes from Version Dated 18 May 2021

Unicode Version has been updated.

Changes from Version Dated 24 January 2024

Adopted from the Second Level Reference LGR for the Korean Language [Ref-LGR-ko-Kore] without normative changes.

References

General references for the language:

• Wikipedia: “Korean language”,
  https://en.wikipedia.org/wiki/Korean_language

• Omniglot: Korean
  https://www.omniglot.com/writing/korean.htm

Other references cited in this document:

[Ref-LGR-ko-Kore]

ICANN, Second Level Reference Label Generation Rules for the Korean Language (ko-Kore), 24 January 2024 (XML)
https://www.icann.org/sites/default/files/packages/lgr/lgr-second-level-korean-hangul-language-24jan24-en.xml
non-normative HTML presentation:
https://www.icann.org/sites/default/files/packages/lgr/lgr-second-level-korean-hangul-language-24jan24-en.html

[RFC 7940]

Davies, K. and A. Freytag, “Representing Label Generation Rulesets Using XML”, RFC 7940, August 2016,
https://www.rfc-editor.org/info/rfc7940

[Unicode 11.0.0]

The Unicode Consortium. The Unicode Standard, Version 11.0.0, (Mountain View, CA: The Unicode Consortium, 2018. ISBN 978-1-936213-19-1)
https://www.unicode.org/versions/Unicode11.0.0/

In the listing of the repertoire by code point, references starting from [0] refer to the version of the Unicode Standard in which the corresponding code point was initially encoded. Other references (starting from [100]) document usage of code points. Entries in the table may have multiple source reference values. In the listing of whole label evaluation and context rules, reference [150] indicates the source for common rules. For more details, see the Table of References below.